This invention relates generally to a method of diagnosing printer problems in order to effectuate repair.
The high degree of complexity of reproduction machines, printers, copiers and the like complicates the detection and identification of problems and repair and service. Service technicians typically use a parametric diagnostic tool (or code) to evaluate operation of the device. These parametric diagnostic tools may reside in the device or may be downloaded by a service technician at the time of service. If the diagnostic tools are downloaded on the device at the time of field servicing, a computer or internet connection is typically required. U.S. Pat. No. 5,768,495 describes a system by which a printer could be serviced in a remote location by downloading full diagnostic code to the printer from a portable device without having to directly connect the printer to a computer.
Having parametric diagnostics built into the printer eliminates the need for a co-located computer, portable device or internet connection. However, the parametric diagnostics tests frequently provided only limited troubleshooting assistance and were not able to reduce service costs significantly. Interpreting field generated parametric test data and troubleshooting field failures becomes difficult data without any baseline printer behavior information. Printer specific data gathered during manufacturing, if it exists at all, is only available via a separate query (the service technician calls the factory for the information) or the field technician must remove the printer for in-factory failure analysis.
Even having the printer specific data gathered during manufacture for the particular model of printer may not be useful in interpreting field test results. Such manufacturing data for mass-produced, low cost printers, typically produces a wide range of acceptable results. The field measured value of a particular test for a particular printer may be associated with a failure and yet may fall within the range of acceptable manufacturing results. There is a need for a printer diagnostic method which overcomes the problems of prior methods.
A method of diagnosing a printer, according to the invention, where the printer is one of a particular type, includes performing a series of parametric tests on the printer at the time of manufacture to generate a set of baseline values for the printer and storing the baseline results. The baseline results may be stored remotely or with the printer, or both. A set of maximum parametric test variations for the printer type is generated, such that each maximum parametric test variation is associated with a particular printer fault event. At the time of a suspected printer fault, the same parametric tests are performed and a set of field values generated. The difference between the field value and the baseline value is calculated for each parametric test. If the difference for a particular parametric test is greater than the maximum parametric test variation for that particular parametric test, the particular print fault event associated with the parametric test value may be indicated.
Software for performing the parametric testing may be stored on the printer so that personnel may perform the tests directly on the printer in the field. Alternatively, the testing may be run remotely from a factory, for example. Each time the set of parametric tests is performed, the results may be stored with the baseline values to keep a historical record of the printer""s performance. This information may be used to determine or anticipate (if the difference between a measured value and the baseline value approaches the maximum parametric variation) a particular type of printer fault.
The maximum parametric test variation is the difference between a baseline value and a measured value at the time of a known printer fault. The maximum parametric test variation may be determined from one or more test printers. The set of maximum parametric test variations may be generated in accordance with the following: providing at least one other printer of the same printer type; performing at least one parametric test on the other printer at the time of manufacture to generate a baseline value for that parametric test for the other printer; causing a fault of a known type in the other printer; performing the parametric test on the other printer to generate a fault value; calculating the difference between the fault value and the baseline value; associating the difference with the fault of the known type. If multiple printers are used, an average of all the individual maximum parametric test variations may be used.